ObjectivesThelong-termbenefitoflatereperfusionofinfarct-relatedartery(IRA)afteracutemyocardialinfarction(AMI)iscontroversial,andthebenefitmechanismsremainuncertain.Lowdosedobutaminestressechocardiography(LDSE)canidentifyviablemyocardiumandpredictimprovementofwallmotionafterrevascularization.MethodsSixty-ninepatientswithfirstAMIwhodidnotreceivedearlyreperfusiontherapywerestudiedbyLDSEat5to10daysafterAMI.Wallmotionabnormalityandleftventricularsizeweremeasuredatthesametime.SuccessfulPCIweredoneinallpatientsat10to21daysafterAMIonset.Patientswerepidedintwogroupsbasedonthepresenceorabsenceofviablemyocardium.Echocardiographywasrepeatedsixmonthslater.ResultsTherewere157motionabnormalitysegments.89segments(57%)wereviableduringLDSE.26patients(38%)withviabilityand43(62%)without.Inviablegroup,leftventricularejectionfraction(LVEF)wasincreased(P<0.05),andleftventricularendsystolicvolumeindex(LVESVI)andwallmotionscore(WMS)weredecreased(P<0.05andP<0.01)significantlyat6monthscomparedwithbaseline.Butinpatientswithoutviability,LVEFwasdecreased(P<0.01),andLVESVIandleftventricularenddiastolicvolumeindex(LVEDVI)wereincreased(P<0.05)significantlyafter6months,andtheWMSdidnotchanged(P>0.05).LVEFincreased(P<0.05)andWMSdecreased(P<0.05)onLDSEduringacutephaseinpatientswithviability,buttheywerenotchangedinthenonviablegroup.ConclusionsLaterevascularizationofIRAinpatientswithpresenceofviablemyocardiumafterAMIisassociatedwithlong-termpreservationleftventricularfunctionandlessventricularremodeling.ImprovementofleftventricularsystolicfunctiononLDSEindicateslatephaserecoveryofleftventricularfunctionafterlaterevascularization.
